Molecular detection of Helicobacter pylori antibiotic resistance in stool vs biopsy samples

AIM To compare(1) demographics in urea breath test(UBT) vs endoscopy patients; and(2) the molecular detection of antibiotic resistance in stool vs biopsy samples.METHODS Six hundred and sixteen adult patients undergoing endoscopy or a UBT were prospectively recruited to the study. The Geno Type Helico DR assay was used to detect Helicobacter pylori(H. pylori) and antibiotic resistance using biopsy and/or stool samples from CLOpositive endoscopy patients and stool samples from UBT-positive patients. RESULTS Infection rates were significantly higher in patients referred for a UBT than endoscopy(overall rates: 33% vs 19%; treatment-na?ve patients: 33% vs 14.7%, respectively). H. pylori-infected UBT patients were younger than H. pylori-infected endoscopy patients(41.4 vs 48.4 years, respectively, P < 0.005), with a higher percentage of H. pylori-infected males in the endoscopy-compared to the UBT-cohort(52.6% vs 33.3%, P = 0.03). The Geno Type Helico DR assay was more accurate at detecting H. pylori infection using biopsy samples than stool samples [98.2%(n = 54/55) vs 80.3%(n =53/66), P < 0.005]. Subset analysis using stool and biopsy samples from CLO-positive endoscopy patients revealed a higher detection rate ofresistance-associated mutations using stool samples compared to biopsies. The concordance rates between stool and biopsy samples for the detection of H. pylori DNA, clarithromycin and fluoroquinolone resistance were just 85%, 53% and 35%, respectively. CONCLUSION Differences between endoscopy and UBT patients provide a rationale for non-invasive detection of H. pylori antibiotic resistance. However, the Geno Type Helico DR assay is an unsuitable approach.

Can bacterial virulence factors predict antibiotic resistant Helicobacter pylori infection?

AIM To evaluate the association between virulence factor status and antibiotic resistance in Helicobacter pylori(H. pylori)-infected patients in Ireland. METHODS DNA was extracted from antral and corpus biopsies obtained from 165 H. pylori-infected patients. Genotyping for clarithromycin and fluoroquinolone-mediating mutations was performed using the Genotype Helico DR assay. cag A and vac A genotypes were investigated using PCR. RESULTS Primary, secondary and overall resistance rates for clarithromycin were 50.5%(n = 53/105), 78.3%(n = 47/60) and 60.6%(n = 100/165), respectively. Primary, secondary and overall resistance rates for fluoroquinolones were 15.2%(n = 16/105) and 28.3%(n = 17/60) and 20%(n = 33/165), respectively. Resistance to both antibiotics was 12.4%(n = 13/105) in treatment-na?ve patients, 25%(n = 15/60) in those previously treated and 17%(n = 28/165) overall. A cag A-positive genotype was detected in 22.4%(n = 37/165) of patient samples. The dominant vac A genotype was S1/M2 at 44.8%(n = 74/165), followed by S2/M2 at 26.7%(n = 44/165), S1/M1 at 23.6%(n = 39/165) and S2/M1 at 4.8%(n = 8/165). Primary clarithromycin resistance was significantly lower in cag A-positive strains than in cag A-negative strains [32%(n = 8/25) vs 56.3%(n = 45/80); P = 0.03]. Similarly, in patients infected with more virulent H. pylori strains bearing the vac A s1 genotype, primary clarithromycin resistance was significantly lower than in those infected with less virulent strains bearing the vac A s2 genotype, [41%(n = 32/78) vs 77.8%(n = 21/27); P = 0.0001]. No statistically significant association was found between primary fluoroquinolone resistance and virulence factor status.CONCLUSION Genotypic H. pylori clarithromycin resistance is high and cag A-negative strains are dominant in our population. Less virulent(cag A-negative and vac A S2-containing) strains of H. pylori are associated with primary clarithromycin resistance.

Combined antrum and corpus biopsy protocol improves Helicobacter pylori culture success

BACKGROUND Helicobacter pylori(H.pylori)causes chronic gastritis,peptic ulcer disease,gastric adenocarcinoma and mucosa-associated lymphoid tissue lymphoma.Eradication rates have fallen,mainly due to antimicrobial resistance.Consensus guidelines recommend that first-line treatment is based on the local prevalence of antimicrobial resistance and that rescue therapies are guided by antimicrobial susceptibility testing(AST).However,H.pylori culture is challenging and culture-based AST is not routinely performed in the majority of hospitals.Optimisation of H.pylori culture from clinical specimens will enable more widespread AST to determine the most appropriate antimicrobials for H.pylori eradication.AIM To determine whether dual antrum and corpus biopsy sampling is superior to single antrum biopsy sampling for H.pylori culture.METHODS The study received ethical approval from the joint research ethics committee of Tallaght University Hospital and St.James’s Hospital.Patients referred for upper gastrointestinal endoscopy were invited to participate.Biopsies were collected in tubes containing Dent’s transport medium and patient demographics were recorded.Biopsies were used to inoculate Colombia blood agar plates.Plates were incubated under microaerobic conditions and evaluated for the presence of H.pylori.Statistical analyses were performed using Graphpad PRISM.Continuous variables were compared using the two-tailed independent t-test.Categorical variables were compared using the two-tailed Fisher exact test.In all cases,a P value less than 0.05 was considered significant.RESULTS In all,samples from 219 H.pylori-infected patients were analysed in the study.The mean age of recruited patients was 48±14.9 years and 50.7%(n=111)were male.The most common endoscopic finding was gastritis(58.9%;n=129).Gastric ulcer was diagnosed in 4.6%(n=10)of patients,while duodenal ulcer was diagnosed in 2.7%(n=6).Single antrum biopsies were collected from 73 patients,whereas combined antrum and corpus biopsies were collected from 146 patients.There was no significant difference in age,sex or endoscopic findings between the two groups.H.pylori was successfully cultured in a significantly higher number of cases when combined antrum and corpus biopsies were used compared to a single antrum biopsy[64.4%(n=94/146)vs 49.3%(36/73);P=0.04)].CONCLUSION Combined corpus and antrum biopsy sampling improves H.pylori culture success compared to single antrum biopsy sampling.